1. Field of the Invention
The present invention relates to a process for the separation and recycling of NO.sub.x gas constituents through adsorption and desorption on a molecular sieve. The molecular sieve is presently initially passed through by NO.sub.x -containing gas sequential alternating process steps until the molecular sieve is saturated with NO.sub.x, and thereafter is regenerated through the introduction of gas.
2. Discussion of the Prior Art
The utilization of a molecular sieve for the separation of nitrous gas constituents from a gas flow is known. During the conduction of waste gas through the molecular sieve, the NO.sub.x gas constituents are bound through adsorption. After a predetermined operating period, the molecular sieve becomes saturated and must be regenerated. Consequently, for a continuous operation it is necessary to connect at least two containers which contain molecular sieves in parallel with each other, and to operate them alternatingly; referring to Norton GmbH, chemical process products, "Zeolon acid resistance molecular sieves", Bulletin Z-51-R1. The molecular sieves are cleansed, after shutting off of the gas flow which is to be purified, through heating, pressure changes or through the intermediary of a scavenging medium, which does not contain the components adsorbed on the molecular sieve. In all of the previously mentioned measures, the nitrous gas constituents desorb from the molecular sieve and are removed. The molecular sieve is, thereafter, again capable for the taking up of NO.sub.x gas constituents.
However, it is advantageous that for the cleaning of the molecular sieve during the desorption of NO.sub.x gas constituents, it is necessary to employ either a complex pumping out or the use of additional carrier gases, which take up the desorbing materials and remove them from the molecular sieve. In the case where there are employed additional carrier gases, the deleterious gas constituents must, in addition, be again isolated from a gas mixture in order to recover the NO.sub.x gas constituents in a concentrated form.